Unlike 2016, even casual observers of political polling should have expected the 2018 midterm election results.
Pre-election polls indicated the House was likely to move toward Democrats and the Senate toward Republicans. This prediction foretold an unusual midterm outcome, one last seen in 1982 – and it is exactly what happened.
Democrats came in to Election Day with a seven-point advantage in the national generic ballot (per the Real Clear Politics average), then won the popular vote for House candidates by eight points en route to a 37-seat gain (as of today).
For the second election in a row, the Fox News national poll tracked election outcomes almost exactly — the final national poll among likely voters had the Democratic advantage in the generic House vote at seven points. In 2016, the last Fox News national poll had Hillary Clinton up by four points, and she won the national popular vote by just over two.
On the Senate side, Fox News polled five races three times in the fall. Two were open seats left by retiring Republicans (Arizona and Tennessee); three featured Democratic incumbents in states Donald Trump won by 18 points or more (Indiana, Missouri, and North Dakota). These battleground states were indicative of the favorable 2018 Senate map for Republicans. Democrats were defending 26 seats, including 10 in states won by Donald Trump in 2016. Republicans had just nine seats to defend.
The third and final round of Fox News polling for each state was released October 31, a week before the election.
In the two open-seat states, Arizona and Tennessee, the final Fox News poll margins were almost dead on compared to election outcomes.
The final Fox News polls in Missouri, Indiana, and North Dakota had the Democratic incumbents well under 50 percent and within three percentage points of the Democrat’s eventual vote share. As is typical of races featuring incumbents, late deciders broke disproportionately for the challengers; this dynamic reinforces the conventional wisdom that a Senator who hasn’t earned a voter’s support over the course of a six-year term is unlikely to do so in the closing days of a campaign.
Analysis accompanying the final poll release mentioned the unsettled nature of these races, and noted that in Indiana the incumbent Democrat’s seven-point lead obscured his vulnerability in the closing week.
Below is a recap of Fox News polling in each state compared to the election outcome.
The early September Fox poll showed Democrats had an opportunity to pick up the seat vacated by retiring Sen. Jeff Flake. Democrat Kyrsten Sinema topped Republican Martha McSally 47 to 44 percent, and Sinema was also viewed more favorably. Our next two polls showed the race tightening to a dead heat. That race was so close that it took a full week to count the votes and declare Sinema the winner.
The early September Fox News poll on the race to fill retiring Tennessee Sen. Bob Corker’s seat showed a slight opening for a Democratic pickup. Democrat Phil Bredesen trailed Republican Marsha Blackburn 44 to 47 percent, he had slightly better favorability ratings and eight percent of voters were undecided. As the campaign progressed, undecideds in this heavily Republican state coalesced around Blackburn. The final Fox poll showed Blackburn up by nine, which closely matches her winning margin.
Indiana Sen. Joe Donnelly won his seat in 2012 with 50 percent of the vote. Yet he never came close to that number in Fox News’ pre-election polling, a clear warning sign for any incumbent. The Fox News poll had him at 43 percent for much of the race, peaking at 45 percent a week before Election Day. He wound up at exactly 45 percent, while Republican challenger Mike Braun got 51 percent of the vote.
Donnelly’s peril was underscored by an unusually unsettled Indiana electorate. In our final poll, seven percent of voters supported third-party candidates and nine percent were undecided. More than two-in-ten said they still might change their mind and back a different candidate. This kind of uncertainty rarely bodes well for incumbents, who count on their track record to convince voters.
While our final horserace number in Indiana showed Donnelly with a slight lead, the Democrat’s low overall support and the fluid electorate was a good sign for Braun. The analysis released with the Fox poll results noted, “Donnelly being under 50 percent bodes well for the less well-known challenger.” We also noted the likelihood of a collapse of support for the Libertarian candidate, which clearly helped the Republican.
The dynamics in Missouri were similar to those in Indiana. Two-term Democratic Sen. Claire McCaskill was stuck in the low 40s in Fox News polling (44 percent in early September, 43 percent in late October), and her Election Day tally (46 percent) was not much better.
Meanwhile, our polling again suggested an unsettled electorate, with four percent backing third-party candidates, nine percent undecided, and two-in-ten saying they might still change their mind about who to support. As in Indiana, these voters broke toward the lesser-known challenger.
From the start, the Fox News poll in North Dakota illustrated Republicans’ advantage in the battle for the Senate. In early September, Democratic Sen. Heidi Heitkamp trailed Republican Kevin Cramer 44 to 48 percent, a perilous position for any incumbent (not to mention one in a state Trump won by 36 points). Heitkamp garnered just 41 percent in early October, shortly before she voted against confirming Brett Kavanaugh. The final Fox News poll had her at 42 percent and down by nine; she ultimately received 44 percent of the vote and lost by 11.